This guide was written by vurbal.
Software used in this guide
Start by installing AviSynth. If you decide to change the install location from the default (C:\Program Files\AviSynth 2.5) make a note of where it is. You'll need this information later to install plugins. Next install AVSEdit. The installer will check to see if your system has Microsoft's .NET 1.1 Framework installed. If it's not already installed you'll see a dialog prompting you to download and install it.